The proposed research extends our existing work on the parsing of sentences to topics in sentence-interpretation. We concentrate on the processing of elliptical constructions, asking questions about how ellipses are interpreted and about the roles that focus, presupposition, processing domains, and prosody play in interpreting elliptical sentences. The immediate goal of the research is to explore how normal adult readers and listeners go beyond the process of perceiving the structure of sentences to constructing a semantic interpretation of a sentence and integrating it with discourse. Its health-related implications are long-term but substantial. Just as advances in psycholinguistic theory over the past two decades have had substantial impact on our understanding of language disorders, most notably aphasia, we expect that a better understanding of the processing of elliptical sentences and the integration of such sentences with discourse will lead to better understanding of the limitations of language use in aphasia. We propose a variety of on-line and off-line experiments to determine readers' and listeners' initial interpretations of ambiguous sentences and to determine the difficulty of comprehending unambiguous sentences with different structures. Our experiments treat a fairly wide range of topics involved in the interpretation of elliptical sentences, including the effects of the structure of the antecedent of an ellipsis, the effects of processing domains, and the effects of focus and other semantic factors. These topics are integrated by explicit hypotheses that we propose, including the copy-alpha proposal and the conjunction principle, together with claims about how a reader or listener aligns corresponding phrases of one or more sentences in the process of filling in ellipses.